Method of refining lubricating-oil stocks



. in various forms.

Patented Apr. 20, 1926.

UNITED STATES JAMES W. WEIR, OF FILLMORE, CALIFORNIA.

METHOD OF REFINING LUBRICATING-OIL STOCKS.

No Drawing.

To all whom it may concern:

Be it known that I, J AMES W. WEIR, a citizen of the United States, residing at Fillmore, in the county of Ventura and State of California, have invented a new and useful Method of Refining Lubricating- Oil Stocks, of which the following is a specification.

This invention relates to a method of refining lubricating stocks from mineral or petroleum oils.

Lubricating oil stocks fromfmineral or petroleum oils are generally refined by treating the stocks with sulfuric acid'followed by a removal of the acid sludge produced and a washing and neutralizing of the treated oil.

In my copending application Serial No. 545,538, filed March 21,1921,which has been granted as Patent No. 1,564,501, there is described a method for treating lubricating oil stocks in which the stock, after an acid treatment and removal of the major portion of the sludge, is-finished without the use of caustic soda through a itating the stock with a comminuted solid adsorbent material at a temperature at which the reaction products left in the oil decompose, and thus are caused to adhere to the comminuted sludge.

As ointed out in my copending application erial No. 30,356, filed May 14, 1925, with certain classes of oils there isleft in the oil subsequent'to an acid treatment a certain amount ofsuspended acid sludge or pepper which is not always removed by the hot treatment with. the comminuted solids unless an excessive quantity thereof is employed, and if not removed causes the oil to darken after standing. Said copending application described a method by which this class of acid, sludge can be first removed from the acid treated stock prior to the treatment of the stock with a comminuted solid-for removing the colloidally suspended'reaction products therefrom.

When certain classes of lubricating oil stocks are treated by the improved method of said last mentioned copending application, there still may be present in the finished oil a quantity of sulfur compounds These sulfur bodies, in addition to being detrimental to the lubricating value of the oil, will also cause it to darken and discolor upon standing for any appreciable length of time, thus impairing the appearance of the oil and decreasing its Application filed May 14, 1925. Serial No. 30,357.

market value. These sulfur compounds may be present 'in the original lubricating oil stock before acid treatment, or be possibly formed therein during such treatment.

There is generally found, however, that lu bricating oil stocks which have been sub- I have discovered that by a treatment of the lubricating oil stocks in a certain way withlitharge or lead oxide (PhD) in com nection with the removal (if the colloidal soluble acid sludge with a comminuted solid adsorbent material, as in the process of my copending application Serial No. 545,538, which has been granted as Patent No. 1,564,- 501, the sulfur bodies or compounds may be removed therefrom, particularly when the oil has been subjected to a prior cracking operation.

The particular chemical reaction by which 7 the litharge is able to remove these sulfur compounds and bodies during this stage of the treating process is not definitely known. The removal of-the sulfur compounds may be accomplished through a chemical reaction resulting. in the formation of lead sulfide or sulfate, or the sulfur compounds may be polymerized out of the acid stock by oxidation of the sulfur compounds, or they may be removed by a catalytic action of the lead oxide in the presence of the finely divided comminuted adsorbent material, and under the influence of heat. .The litharge may be used in connection with or in combination with colloidal clays, fullers earth or any other decolorizing agent where or whenever heat is employed during the treatment of a lubricating oil stock, for example, litharge may be used in the methods of treatment of lubricating oils described in patents issued to Chappell and Moore, .LTOS. 1,404,374 and 1,404,375, or similar methods.

The quantity of litharge added to the comminuted solid substance will depend entirely upon the grade-of oil, with reference to objectionable sulfur content upon which it is to, be used. Under ordinary conditions, the amount added to the comminuted solid operation may be widely varied for operating upon oils of different character, without departing from the spirit of this inventlon.

The lubricating oil stock is first treated with sulfuric acid in any usual or preferred manner, the sulfuric acid being added to the lubricating oil stock in one portion or in a plurality of separate portions, as desired, with an intermediate drawing oil of sludge between each application. After the desired acid treatment, the mixture is allowed to settle and the major portion of thesludge or that portion of the sludge which will settle is then removed from the lubricating oil stock. There still remains in the lubricating oil stock two classes of acid sludge .or reaction products, one portion being in the form of so-called pepper or finely divided solid sludge-held mechanically suspended in the lubricating stock, and another form of sulfuric acid sludge held 1n a sort of colloidal suspension on solution in the stock. Preferably, the oil is then treated to remove this solid suspended sludge, for which purpose there is added to the lubricating oil, a quantity of comminuted solid adsorbent material to adsorb, gather or coagulate said sludge into sufiiciently large particles of sufficient weight so that the same may settle to the bottom of the mass, where the same may be removed. The quantity of comminuted solid substance necessary to accomplish this purpose is generally about one ton of the solid substance to 30,000 gallons of lubricating oil stock to be treated, al-

q though it is to be understood that the or coagulated sludge the oil stock is then i amount may be varied with different lubricating oils.

The comminuted solid substance employed may be either comminuted granite, magnesium silicate, fullers earth, dratom'aceous earth, decolorizing agent made by acid treated montmorillonite, and like clay material, certain materials of the tale or serpentine group which may or may not have decolorizi'ng properties.

After the oil is freed of said comminuted solid substance and the adsorbed, gathered transferred to. a suitable treating or mixin tank equipped with the proper mechamca apparatus for agitation and means for heatmg. A suitable required quantity .of the finely divided comminuted solid adsorbent material is then added during agitation of the lubricating oil stock under treatment, the

quantity generally being one ton of the solid substance to 5,000 gallons of the lubricating oil stock. The solid here added, may, if desired, be merely a further application ofciently (approximately 180 to 500 F.,preferably 360 F.) to cause the remaining sludge in the lubricating oil stock to decompose.

The oil is held under heat until the sulfur dioxide products of the slud e decomposition have been substantially driven off. This treatment, may, if desired be aided by the passing of non-oxidizing gas through the mass being treated. Thereafter, preferably within a relatively short time'and while the mixture is still under agitation, litharge is added in sufficient quantities to remove the objectionable sulfur compounds from the lubricating oil stock, the amount of lithargenecessa being approximately 1% to 5% by Weig t of the comminuted solid adsorbent material which is employed. The agitati-on of the mixture with the added litharge is continued until reaction is completed, after which the adsorbed and combined compounds; with the comminuted adsorbent material and litharge, may be removed from the lubricating oil stock by settling, centrifugal force, filtration through filter blankets with a filter press, or by any well known means of separating solids or semi-solids from liquids. Subsequently, the oil may be brightened by being-blown with air in the usual manner, and is preferably thereafter reduced in temperature, although it is not. essential to provide apparatus or methods for quickly cooling the oil.

Any trace of foreign substance left remaining in the oil after the brightening operation may be removed by passing the same through a filter or strainer of material such as fullers earth of approximately from 30 to 60 mesh.

By the method above described, such acid sludge or acid reaction products are removed by adsorption with comminuted solid mate;

rials with substantially no chemical reaction, and objectionable sulfur bodies are removed by litharge. Thus the oil is purified without injurious compounds beingv formed which remain in the oil after treatment or must be removed by further processing.

It is pointed out that the treatment herein described involving the use of litharge' is not adapted in all casesfor removing of all the sulfur compounds or bodies from the oil, but that in certain classes of lubricating oil stocks, particularly those having been subjected to a cracking reaction, a substantial reduction in the sulfur content is hereby effected. I L

' scope of the appended claims.-

I claim:

1. A method of refining lubricating oilstocks which comprises treating the oil with sulfuric acid, settling and removing the settled sludge, then adding eomminuted solid adsorbent material and agitating the same in the oil at a temperature below thedecomposing temperature of the sludge or acid reaction products of the oil, separating the adsorbent material with the sludge thus gathered from the oil stock, then adding eomminuted solid adsorbent material to the oil stock and heating the mixture to a temperature suflicient to decompose the remaining sludge, and liberating sulfur dioxide therefrom, then adding litharge to the mixture, and separating the purified oil stock from the remainder of the admixture.

- 2. The method of refining a lubricating oil-stock, which comprises treating the oil with sulfuric acid, settlin and removing the major portion of the sludge, then agitating the stock with eomminuted adsorbent material at a temperature below the decomposing temperature of the sludge, separating the adsorbent material with the mass adsorbed thereon from the oil stock, then agitating the oil stock with eomminuted solid adsorbent material at a temperature not less than 180-F. to decompose the remaining sludge and liberate the sulfur dioxide therefrom, then adding litharge to the mixture to remove objectionable sulfur compounds from the oil stock, and separating the purified oil stock from the admixture.

3. Themethod of refining lubricating oil stocks, which comprises treating the oil with sulfuric acid, settling and removing the ma- 1' or portion of the sludge, agitating the stock with eomminuted adsorbent material at a temperature below 180 F., separating thev adsorbent materialpwith the sludge gathered thereby from the oil stock, then agitating the oil stock with eomminuted-solid adsorbent material at a temperature suflici'ent to do compose the remaining sludge and liberate sulfur dioxide therefrom, then agitating the mass with litharge to remove the objectionable sulfur compounds from the oil stock, blowing the mixture with a non-oxidizing gas during said treatment,- and separating the purified oil stock' from the admixture.

4. A method of refining lubricating oil stocks, which comprises treating the oil with sulfuric acid, settling and removing the major portion of the sludge,'treatin the oil stock with eomminuted solid adsor ent material at a temperature suflicient t0 decompose the sludge present anddiberate sulfur dioxide therefrom,- then adding ,litharge to the mixture, and thereafter separating the oil stock from the admixture.

Signed at Los Angeles, California, this 7th day of May 1925.

JAMES w. WEIR. 

